Spatially Resolved Imaging of Electrocaloric Effect and the Resultant Heat Flux in Multilayer Capacitors

Multilayer capacitors (MLCs) are one of the most studied electrocaloric (EC) systems because they are regarded as the most promising configuration for developing electrocaloric prototype devices. Indeed, (1) they combine thin films prone to exhibit the so-called giant EC effect; (2) they are made of several hundred active layers; and (3) their internal interdigitated structure alternating highly thermally conductive electrodes with EC layers should dramatically increase their propensity to extract heat. Although the latter has been foreseen by modeling, it has never been observed experimentally. Here we use an infrared camera to observe for the first time the heat flux crossing standard EC MLCs during operation. Interestingly, we observed that heat flux perpendicular to the terminal-terminal direction accounts for only 20% of the total heat flux. This observation strongly suggests that all future electrocaloric cooling devices should rely on a design favoring heat exchange through the MLC terminals.